1. Field of the Invention
The present invention relates to a piezoelectric/electrostrictive microactuator and manufacturing method thereof. In particular, the present invention relates to a piezoelectric/electrostrictive microactuator whose structure is simple because of being membraneless and easy of low voltage driving and also it relates to a manufacturing method of such an actuator.
2. Description of the Prior Art
An ink jet printer head actuator using a piezoelectric substance is usually composed of an infrastructure made of a vibration plate (22) and a chamber (20), a piezoelectric/electrostrictive film (26) which undergoes mechanical transformation if electricity is applied as the piezoelectric/electrostrictive film is connected on the vibration plate (22), and electrodes (24) (28) which transmit electricity to the piezoelectric/electrostrictive film (26) as in FIG. 2.
The piezoelectric substance of an actuator has characteristics poling (by which a directionality is given at piezoelectric substance when electric field is applied) when electric field is applied. If electricity is supplied to an upper electrode and a lower electrode formed on and under piezoelectric substance under poling state, the piezoelectric substance located between electrodes undergoes mechanical deformation or vibrates with recycling of transformation and restoration.
In the ink jet printer head, ink is jetted to a record medium as the vibration plate undergoes mechanical transformation thickwise if the piezoelectric substance of actuator vibrates.
Thus in the ink jet printer head, the infrastructure composed of the chamber and the vibration plate is an important factor for the operation of the actuator.
Metal, resin, ceramic etc. are used as material of the chamber plate and the vibration plate of the actuator using the piezoelectric substance.
Ordinarily chamber structure is formed mainly by half etching of wet etching method in case where metal is used as the material; three dimensional structure is formed by injection molding method in case where resin is used as the material; and three dimensional structure is formed by integrated molding of vibration sheet and punching of the sheet in case where ceramic is used as the material.
It is important to supply uniform vibration plate when manufacturing the infrastructure of the chamber and the vibration plate by the methods.
And because the actuator is made by forming a piezoelectric/electrostrictive film on the vibration plate, void may easily be formed between the vibration plate and the piezoelectric/electrostrictive film, and by way of which void there is worry of occurring partial crack.
The present invention to solve the problem aims to provide a piezoelectric/electrostrictive microactuator of simple structure having no vibration plate by way of direct binding of piezoelectric/electrostrictive film onto a chamber plate done of full etching or punching method, and a manufacturing method thereof.
The present invention to accomplish the purpose features a manufacturing method of a membraneless piezoelectric/electrostrictive microactator comprising the steps of providing a chamber plate; forming a chamber in the chamber plate; forming a piezoelectric/electrostrictive film separately; forming a lower electrode under the piezoelectric/electrostrictive film; bonding the chamber plate and the lower electrode using a bonding layer; and forming an upper electrode on the piezoelectric/electrostrictive film.
Also the present invention features a membraneless piezoelectric/electrostrictive microactuator comprising a chamber; a chamber plate in which the chamber is formed; a lower electrode formed on the chamber plate and covering the chamber; a bonding layer formed between the chamber plate and the lower electrode and bonding the chamber plate and the lower electrode; a piezoelectric/electrostrictive film formed on the lower electrode and vibrating when electrified; and an upper electrode formed on the piezoelectric/electrostrictive film.